In U.S. Pat. No. 2,991,824, recesses 51A, 51B are produced in a preform intended to be cut in order to produce plaster boards, by means of (see in particular FIG. 1 and column 3, lines 29 to 43 of this patent) a conveyor 20 turning around two rolls 21 and comprising a mould strip 25. The preform is then cut at the middle of the recesses so as to produce boards with feathered ends or feathered transverse edges.
In U.S. Pat. No. 2,246,987, recesses are produced in a preform intended to be cut in order to produce plaster boards, by means (see in particular FIGS. 1 and 7) of a conveyor 0 comprising a plurality of bars 23, 38. In one embodiment, recesses are produced on both sides of the board at the same time.
In U.S. Pat. No. 2,168,803, recesses are produced in a preform intended to be cut in order to produce plaster boards, by means of supporting members 21 (see in particular FIG. 1). These supporting members can be temporarily fixed to the lower facing, for example by stapling. These supporting members are applied in particular before the facing receives the gypsum paste, but it is also possible to envisage applying them after pouring the paste.
Patent Application WO-A-2005/028171 describes a new board with four feathered edges, as well as production processes, and devices for the production of these boards. The Applicant is also the proprietor of the patent applications WO-A-03/041930, WO-A-03/072326 and WO-A-2004/009309, as well as WO-A-03/084724. These patent applications use laths in order to form transverse featherings during the production of the boards.
The processes described are satisfactory from a production point of view, but at the level of the product, it is also sought to improve the rendering of the feathering formed transversely. In particular, a solution is sought which makes it possible to obtain a feathering, which is perfectly symmetrical and perfectly rectilinear.